1. Field of the Invention
The present invention relates to methods of producing longitudinally fine striped type heat seal connector members having a desired length, width and spacing of electrically conductive channels for mechanically and electrically connecting electrode portions of electronic elements, such as, liquid crystal display tubes, or electrochronic display (ECD) panels, solar cells, etc., to terminal portions of printed circuit substrates, or opposing terminal portions of printed circuit substrates to each other.
The present invention relates also to methods of producing longitudinally fine striped type heat seal connector members wherein an electrically conductive specific photoetching resistive pain (photoresist paint) is used to omit a portion of the photoetching process, while providing highly reliable connection property.
2. Related Art Statement
Heretofore, in case when producing the above longitudinally fine striped type heat seal connector members by using a conventional photoetching resistive ink, usually a film of a photosensitive etching-resistive material on a copper foil disposed on a substrate is exposed to a light through a negative mask to develop a desired pattern of electrically conductive circuit of the photocured photosensitive material. Then, the substrate having the photocured pattern thereon is subjected to an etching treatment to dissolve and remove excessive unnecessary unphoto-cured remaining etching resistive material around the photocured pattern of the photocured photosensitive material together with the underlying copper foil layer. Subsequently, the remaining photocured photosensitive etching resistive material on the copper foil of the electrically conductive circuit pattern is removed by a chemical agent, such as, an alkaline material, etc., to expose bare surfaces of the copper foil layer of the conductive circuit pattern. Thereafter, the substrate having the desired circuit pattern is treated in two different ways.
(a) One way is to form an electrically conductive layer of a press heat bonding agent containing conductive fine particles of a metal or graphite, etc., exclusively on the bare surfaces of the copper foil, i.e., solely on the circuit pattern, and then the substrate surface other than the circuit pattern is coated with an electrically insulative press heat bonding agent not containing electrically conductive fine particles in a separate process. Namely, the press heat bonding agent layers are prepared by two steps of preparing the layer of electrically conductive property and preparing the layer of electrically insulative property. PA0 (b) The other way is to form a so-called "electrically anisotropic" heat seal layer on the whole one surface of the substrate, i.e., on the surface of the bare copper foil and on the remaining surface of the substrate around the bare copper foil not having the bare copper foil thereon. Namely, a layer of a press heat bonding agent is applied by coating on the whole one surface of the substrate, which layer of the bonding agent has different degrees of electrical conductivity between lateral direction (x direction) and height or length direction (y direction), the electrical conductivity thereof in height direction (y direction) keeping a certain range of electrically conductive property, and the electrical conductivity thereof in lateral direction (x direction) being very small and assuming relatively rather substantially electrically insulative property, when the composition per se of the press heat bonding layer is press heat bonded under a given condition.
However, these conventional methods have large drawbacks, though they have a few advantages. Namely, though the above method (a) has reliability and comparatively good performance in electrically conductive property, electrically insulative property and press heat bonding property, it necessitates a lengthy or time-consuming process requiring a double labor and materials for forming the press heat bonding layers. In addition, it necessitates a prolonged etching step for directly exposing the copper foil surface of the circuit pattern, complete washing of the circuit pattern to remove the used strong alkaline or the like chemical agent, and cumbersome problem of preventing environmental pollution caused by the used strong chemical agent.
Meanwhile, though the above method (b) is advantageous in that it needs not to provide two layers of press heat bonding agent and only one layer thereof is sufficient, and composition of the anisotropic heat seal layer and use condition thereof are strictly restricted. Moreover, properties of the formed press heat bonding layers fluctuates largely, so that sufficient reliability and stability in conductive property and insulative property are difficult to achieve. In addition, the above large drawbacks of the method (a) relating to the etching can not be avoided.